How many ohms is your speaker? how many ohms is your amp stable to?
Alot of times if you have a speaker that runs at 2 ohms but an amp that is only stable to 4ohms then anything lower than 4 ohms will cause the amp to overheat. As a protection measure amps have a shut off that will cut the power to it when it gets too hot. I would guess this is the problem being that is sounds like the amp will work again when you try to use it again later. (if it were a blown fuse from too much draw you would have to replace the fuse to get it to work again and would therefor know the problem and not be asking)
Alot of times if you have a speaker that runs at 2 ohms but an amp that is only stable to 4ohms then anything lower than 4 ohms will cause the amp to overheat. As a protection measure amps have a shut off that will cut the power to it when it gets too hot. I would guess this is the problem being that is sounds like the amp will work again when you try to use it again later. (if it were a blown fuse from too much draw you would have to replace the fuse to get it to work again and would therefor know the problem and not be asking)